net: ethernet: cortina: Locking fixes

This fixes a probably long standing problem in the Cortina
Gemini ethernet driver: there are some paths in the code
where the IRQ registers are written without taking the proper
locks.

Fixes: 4d5ae32 ("net: ethernet: Add a driver for Gemini gigabit ethernet")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240509-gemini-ethernet-locking-v1-1-afd00a528b95@linaro.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Linus Walleij

drivers/net/ethernet/cortina/gemini.c

@@ -1107,10 +1107,13 @@ static void gmac_tx_irq_enable(struct net_device *netdev,
 {
 	struct gemini_ethernet_port *port = netdev_priv(netdev);
 	struct gemini_ethernet *geth = port->geth;
+	unsigned long flags;
 	u32 val, mask;
 
 	netdev_dbg(netdev, "%s device %d\n", __func__, netdev->dev_id);
 
+	spin_lock_irqsave(&geth->irq_lock, flags);
+
 	mask = GMAC0_IRQ0_TXQ0_INTS << (6 * netdev->dev_id + txq);
 
 	if (en)
@@ -1119,6 +1122,8 @@ static void gmac_tx_irq_enable(struct net_device *netdev,
 	val = readl(geth->base + GLOBAL_INTERRUPT_ENABLE_0_REG);
 	val = en ? val | mask : val & ~mask;
 	writel(val, geth->base + GLOBAL_INTERRUPT_ENABLE_0_REG);
+
+	spin_unlock_irqrestore(&geth->irq_lock, flags);
 }
 
 static void gmac_tx_irq(struct net_device *netdev, unsigned int txq_num)
@@ -1415,15 +1420,19 @@ static unsigned int gmac_rx(struct net_device *netdev, unsigned int budget)
 	union gmac_rxdesc_3 word3;
 	struct page *page = NULL;
 	unsigned int page_offs;
+	unsigned long flags;
 	unsigned short r, w;
 	union dma_rwptr rw;
 	dma_addr_t mapping;
 	int frag_nr = 0;
 
+	spin_lock_irqsave(&geth->irq_lock, flags);
 	rw.bits32 = readl(ptr_reg);
 	/* Reset interrupt as all packages until here are taken into account */
 	writel(DEFAULT_Q0_INT_BIT << netdev->dev_id,
 	       geth->base + GLOBAL_INTERRUPT_STATUS_1_REG);
+	spin_unlock_irqrestore(&geth->irq_lock, flags);
+
 	r = rw.bits.rptr;
 	w = rw.bits.wptr;
 
@@ -1726,10 +1735,9 @@ static irqreturn_t gmac_irq(int irq, void *data)
 		gmac_update_hw_stats(netdev);
 
 	if (val & (GMAC0_RX_OVERRUN_INT_BIT << (netdev->dev_id * 8))) {
+		spin_lock(&geth->irq_lock);
 		writel(GMAC0_RXDERR_INT_BIT << (netdev->dev_id * 8),
 		       geth->base + GLOBAL_INTERRUPT_STATUS_4_REG);
-
-		spin_lock(&geth->irq_lock);
 		u64_stats_update_begin(&port->ir_stats_syncp);
 		++port->stats.rx_fifo_errors;
 		u64_stats_update_end(&port->ir_stats_syncp);